diff --git a/.env.example b/.env.example
index 954e52c..0e1a1ca 100644
--- a/.env.example
+++ b/.env.example
@@ -70,9 +70,10 @@ EXPLORER_ACCESS_DB="/var/lib/explorer/access.db"
 # The __Host- cookie contract requires HTTPS; central mode fails startup if
 # this is disabled. AUTH_ALLOW_INSECURE_HTTP exists only for development.
 EXPLORER_AUTH_COOKIE_SECURE="1"
-# Idle and absolute session lifetimes: 60 minutes and 12 hours.
-EXPLORER_SESSION_IDLE_SECONDS="3600"
-EXPLORER_SESSION_ABSOLUTE_SECONDS="43200"
+# Idle and absolute session lifetimes: 12 hours and 24 hours. Short on
+# purpose: expiry is a silent redirect while the central Auth session lives.
+EXPLORER_SESSION_IDLE_SECONDS="43200"
+EXPLORER_SESSION_ABSOLUTE_SECONDS="86400"
 
 # ── Session and CSRF cookie ─────────────────────────────────────────────
 # Signs the central-login state/PKCE transaction plus the short-lived cookie
diff --git a/README.md b/README.md
index f936d9f..04ff0a1 100644
--- a/README.md
+++ b/README.md
@@ -148,8 +148,8 @@ Neither dotenv file is committed. `.env.example` is the annotated template:
 | `EXPLORER_ACCESS_DB` | central mode | `/var/lib/explorer/access.db` | Deployment-local email access list and app sessions; contains no passwords. |
 | `EXPLORER_AUTH_COOKIE_SECURE` | central mode | `1` | Requires the app-scoped cookie to travel over HTTPS. Keep enabled in production. |
 | `EXPLORER_UI_COOKIE_SECURE` | no | `1` | Requires the search/CSRF cookie to travel over HTTPS. Keep enabled in production. |
-| `EXPLORER_SESSION_IDLE_SECONDS` | no | `3600` | Central-mode Explorer session idle lifetime (60 minutes). |
-| `EXPLORER_SESSION_ABSOLUTE_SECONDS` | no | `43200` | Central-mode Explorer session absolute lifetime (12 hours). |
+| `EXPLORER_SESSION_IDLE_SECONDS` | no | `43200` | Central-mode Explorer session idle lifetime (12 hours). |
+| `EXPLORER_SESSION_ABSOLUTE_SECONDS` | no | `86400` | Central-mode Explorer session absolute lifetime (24 hours). |
 | `EXPLORER_SESSION_SECRET` | central: **yes**; Elcano: recommended | a dev placeholder | Signs central login state and the cookie scoping search jobs to one browser. Generate with `openssl rand -hex 32`. |
 
 ### Authentication
@@ -200,9 +200,12 @@ sudo explorer access revoke user@example.com
 Allowed users receive a random 256-bit, app-only session. Only its SHA-256
 hash is stored in `/var/lib/explorer/access.db`; the host-only
 `__Host-explorer_session` cookie is `Secure`, `HttpOnly`, `SameSite=Lax`, and
-scoped to `/`. Sessions expire after 60 minutes idle or 12 hours total; the
+scoped to `/`. Sessions expire after 12 hours idle or 24 hours total; the
 idle clock is refreshed at most once a minute (the Elcano convention for
 service sessions), so a session can end up to a minute early but never late.
+Expiry costs the user only a redirect: while their central Auth session (30
+days) is live, the handoff signs them back in without a prompt. The short
+app limit bounds a stolen cookie and re-checks the account with Auth daily.
 Revoking an email immediately invalidates all of that email's Explorer
 sessions. Logout is CSRF-protected and revokes only the current Explorer
 session. Auth's signed back-channel endpoint also revokes every local session
diff --git a/app/central_auth.py b/app/central_auth.py
index 26e88d7..e1e71c5 100644
--- a/app/central_auth.py
+++ b/app/central_auth.py
@@ -31,11 +31,18 @@
 from cryptography.hazmat.primitives.asymmetric.ed25519 import Ed25519PublicKey
 
 CENTRAL_AUTH_COOKIE_NAME = "__Host-explorer_session"
-DEFAULT_IDLE_SECONDS = 60 * 60
-DEFAULT_ABSOLUTE_SECONDS = 12 * 60 * 60
+# Application sessions are deliberately short. Expiry costs the user only a
+# redirect: the code handoff signs them back in silently while the 30-day
+# central Auth session is live. The short limit bounds a stolen Explorer
+# cookie and forces a daily re-check with Auth that the account is still
+# enabled. One day absolute, 12 hours idle is the Elcano convention for every
+# application session (owner decision 2026-09-15; see Auth's
+# docs/AUTH_V2_IMPLEMENTATION.md "Application session conventions").
+DEFAULT_IDLE_SECONDS = 12 * 60 * 60
+DEFAULT_ABSOLUTE_SECONDS = 24 * 60 * 60
 # How often a validated session rewrites last_seen_at / idle_expires_at. Every
 # request reads the session; only a request more than this long after the
-# previous touch writes. The idle limit therefore behaves as "60 minutes minus
+# previous touch writes. The idle limit therefore behaves as "12 hours minus
 # at most one minute", never longer, and a page's burst of requests costs one
 # SQLite write instead of one per request. One minute is the convention for
 # every Elcano service with its own sessions (Auth, Explorer, Lens, and
diff --git a/docs/DEPLOYMENT.md b/docs/DEPLOYMENT.md
index f1c28c8..242b419 100644
--- a/docs/DEPLOYMENT.md
+++ b/docs/DEPLOYMENT.md
@@ -180,8 +180,8 @@ but lose to `.env`.
 | `AUTH_SIGNING_PREVIOUS_PUBKEYS` | no | *(empty)* | Comma-separated prior Ed25519 public keys. Rarely needed now: in central mode Explorer also reads Auth's published `/jwks.json` (cached 10 minutes, refreshed once when a token names an unknown key), so an Auth key rotation needs no env edit here. |
 | `EXPLORER_ACCESS_DB` | central mode | `/var/lib/explorer/access.db` | SQLite email access list and Explorer session hashes. Keep it outside the application tree and mode `0600`. |
 | `EXPLORER_AUTH_COOKIE_SECURE` | central mode | `1` | Controls `Secure` on `__Host-explorer_session`. Central mode refuses an insecure setting in production. |
-| `EXPLORER_SESSION_IDLE_SECONDS` | no | `3600` | Explorer app-session idle lifetime. Activity refreshes this deadline but never extends the absolute deadline. |
-| `EXPLORER_SESSION_ABSOLUTE_SECONDS` | no | `43200` | Explorer app-session absolute lifetime. |
+| `EXPLORER_SESSION_IDLE_SECONDS` | no | `43200` | Explorer app-session idle lifetime. Activity refreshes this deadline but never extends the absolute deadline. |
+| `EXPLORER_SESSION_ABSOLUTE_SECONDS` | no | `86400` | Explorer app-session absolute lifetime. |
 
 Central mode owns no passwords. Manage only the local authorization list:
 
diff --git a/scripts/bootstrap.sh b/scripts/bootstrap.sh
index ce52cbe..4c79fc8 100755
--- a/scripts/bootstrap.sh
+++ b/scripts/bootstrap.sh
@@ -164,8 +164,8 @@ AUTH_SIGNING_PUBKEY="${AUTH_SIGNING_PUBKEY:-}"
 AUTH_SIGNING_PUBKEY="$(prompt AUTH_SIGNING_PUBKEY "auth service AUTH_SIGNING_PUBKEY, base64 (run 'auth pubkey' on the auth host; blank to set later)" "$AUTH_SIGNING_PUBKEY")"
 
 EXPLORER_ACCESS_DB="${EXPLORER_ACCESS_DB:-/var/lib/explorer/access.db}"
-EXPLORER_SESSION_IDLE_SECONDS="${EXPLORER_SESSION_IDLE_SECONDS:-3600}"
-EXPLORER_SESSION_ABSOLUTE_SECONDS="${EXPLORER_SESSION_ABSOLUTE_SECONDS:-43200}"
+EXPLORER_SESSION_IDLE_SECONDS="${EXPLORER_SESSION_IDLE_SECONDS:-43200}"
+EXPLORER_SESSION_ABSOLUTE_SECONDS="${EXPLORER_SESSION_ABSOLUTE_SECONDS:-86400}"
 
 # ── Caddy / TLS intent (actual install happens in step 7) ────────
 # Collect answers now so the rest of the run has no surprise prompts.
diff --git a/tests/test_central_auth_endpoints.py b/tests/test_central_auth_endpoints.py
index 0112726..8872348 100644
--- a/tests/test_central_auth_endpoints.py
+++ b/tests/test_central_auth_endpoints.py
@@ -166,7 +166,7 @@ def test_callback_issues_app_scoped_cookie_for_allowlisted_email(
     assert "Secure" in cookie
     assert "SameSite=lax" in cookie
     assert "Path=/" in cookie
-    assert "Max-Age=43200" in cookie
+    assert "Max-Age=86400" in cookie
     assert "Domain=" not in cookie